Just in case you haven't played the game yet, I've mentioned that there will be spoilers in this topic. This is your final warning over spoilers.
I've read over lots of places in the internet over TWEWY, some of which were over the Entry Fees, the thing a person most cares about, that players gave to play in the Game. I'm going to go over what the entry fees are throughout the game. Most are confirmed, but some are never said in the game. I believe my ideas on the unexplained Entry fees are very logical.
Neku - His memory. This is very obvious. It is explained during Day 8, and can be inferred during the entire first week as he cannot remember anything besides his name.
Shiki - Her appearance. This is obvious as well. It is revealed during Day 6 when Neku and Shiki see Eri in the crowds.
Beat - Rhyme's memories of him. Not quite as obvious until the final day. It is said by Konishi that this is the case.
Rhyme - Her goals, ambitions, and dreams. Though not said outright, it can be inferred that this is true. She admits that she "had never had a dream" during Day 4. Beat later says during Day 17 that she had lots of dreams before she died, and that he lied about is dream about becoming the best skater in the world.
Megumi - His ability to roam Shibuya. He is never seen outside of The God's Pad, The Room of Reckoning, and the space in between. This seems likely, as he is very concerned about Shibuya's existance, and utters, "The streets I know and love... you're going to erase them." before he is erased himself.
Neku - Shiki Misaki. This is a bluff on Megumi's part, as he couldn't restore Shiki to life. However, ironically, this is enough for Neku to focus everything on this game to win.
Neku - The other players. Revealed on the first day of this Game.
Beat - Rhyme. Konishi takes Rhyme's Noise as his entry fee. This explains how Rhyme appears at the end of the game, alive and well. She lost the first game, however, and lost her Entry Fee along with it.
Neku - His ability to be with Joshua. He understands that Joshua killed him. He is extremely angry with Joshua just before the start of his fourth game. However, Joshua is the only person that has actually connected with him. Joshua dislikes people just as much as Neku does. Neku values this friendship, and is unable to shoot his friend. He lost his fourth game, and thus, he cannot ever see Joshua again. This is later enforced when the player collects all 22 secret reports and completes the game again. There is a secret scene where it shows Hanekoma speaking with Joshua, and they are both looking down at the four Players. He says that Joshua "looks down." This is because Joshua is unable to celebrate with them, due to Neku's Entry Fee. Before the credits roll, Neku is doing his little speech about how much he has learned and that "he's got friends now." He is speaking this all to Joshua, backed up by the "I can't forgive you yet" sentences. He can't believe that he was used just to win a Game, and that after all was through, Joshua was once again willing to shoot him again. Neku's last words were, "See you there?" asking if Joshua would be able to meet up with them again, though this isn't possible.
Any thoughts on the matter are welcome. Anything you'd like to oppose in my theories is welcome, though I'm fairly sure I have very accurate assumptions.
Nao and Sota are not mentioned, as their entry fees are not apparent and cannot be inferred.